To find the atmospheric pressure which is air pressure use a serviceable barometer. For measurement of pressure of air in pipes, automobile tires, cylinders, use special manometers. If it is possible to calculate vessel volume with gas and its temperature, pressure can be calculated on ideal gas law which can consider air.
It is required to you
- aneroid barometer, manometer, thermometer, scales
Instruction
1. On each body which is on the Earth's surface air of which the atmosphere consists makes pressure. This pressure is also called atmospheric. To measure it take the ordinary aneroid barometer in which there is a hollow metal box changing the volume depending on the size of atmospheric pressure. Pressure is reflected in its scale in the atmospheres or in pascals.
2. If it is necessary to measure gas pressure in a tight vessel, use the manometer with the corresponding class of measurements. Using the electronic manometer, adjust it on the necessary accuracy. For this purpose install the manometer on a cylinder in which for these purposes there has to be a special union. The majority of manometers measure pressure in kg/cm² or the atmospheres. For the transfer from one size to another consider that 1 kg/cm²=1 atmosfere100000 pascals.
3. If there is no manometer, then calculate air pressure in a tight vessel with the known volume. Pump out from it air and weigh on scales. Then again pump in it air and again find the mass of a vessel. The difference of mass of an empty and full vessel will also be equal to the mass of the air which is contained in it. Express weight in grams. Provided that a boundary a cylinder and the environment freely occurs heat exchange, air temperature in and outside of a vessel it is possible to consider identical. Measure it by the thermometer and transfer to kelvins, having added to value in degrees Celsius number 273.
4. When calculating consider that the molar mass of air is equal 29 grams on mol. Find the work of mass of air in a vessel, on its temperature and number 8.31 (universal gas constant). Consistently divide result into the molar weight, and the vessel volume expressed in cubic meters of P=m·R·T / (M•V). Receive result in pascals